1. Technical Field
This invention generally relates to a positioning apparatus for use during hitching a pickup truck or other towing vehicle to a trailer or other towed vehicle. More particularly, this invention relates to a positioning apparatus for aligning the coupling elements or the two vehicles as the towing vehicle is backed up or driven toward the towed vehicle and for indicating when the coupling elements are properly positioned for coupling.
2. Discussion
Hitching a vehicle to a trailer can be a long and frustrating process, especially when attempted by a single person. Because the coupling elements (i.e., ball and hitch) on the vehicle and trailer are normally not visible from the driver's seat, the driver must periodically stop the vehicle and inspect the alignment and position of the ball and hitch before moving the vehicle closer to the trailer. Even with frequent visual inspections, some misalignment of the ball and hitch normally results. A driver must then repeat the process or, if possible, manually shift the tongue and thus the hitch of the trailer over the ball so that the two vehicles can be hooked up. Complicating the maneuvering is the fact that a driver can become easily confused as to which direction to turn the front wheels in order to back the vehicle in the desired direction.
In an attempt to improve on this manual method, prior guidance systems have been designed for assisting a driver in maneuvering a vehicle toward a trailer. U.S. Pat. No. 4,938,495 to Beasley et al., for example, discloses a trailer hitch guide that uses an infrared light emitter mounted on a trailer and powered by a battery in the isolated unit. A support bar with alignment sensors is mounted on the back of a towing vehicle. The emitted infrared light produces a light field which can be detected by the receiving sensors on the vehicle. Beasley recites that depending on the orientation of the receiving sensors to the field, the alignment and position of the vehicle relative to the trailer can be determined from a direction indicator visible to the driver. The Beasley device, however, has a number of drawbacks. For example, the isolated light emitter mounted on the trailer runs on a battery in the unit and needs to be turned on before use and shut off after use. The same is true with the second sensor needed for the positioning of coupling. This leaves a great margin for human error as well as replacement and maintenance of the battery. Some vehicles may not have a support bar located in the rear bumper for mounting and this is cumbersome in design. Also, it is believed that the Beasley device may not always indicate accurately the relative position of the hitch and ball due to limitations of the Beasley approach.
Other exemplary prior devices for guiding the backing of a vehicle to a trailer are disclosed in U.S. Pat. No. 4,199,756 to Dito, and U.S. Pat. No. 3,418,628 to Fenner. These devices rely on mechanical contact switches or visual alignment mechanisms that are cumbersome and/or which must be mounted temporarily to a vehicle and trailer for use when attempting to back up and hitch the two together.